1. Field of the Invention
This invention relates to a method for the manufacture of an aromatic polyester-polycarbonate. More particularly, this invention relates to an advantageous method for commercially manufacturing an aromatic polyester-polycarbonate which possesses excellent mechanical properties, thermal stability chemical resistance and transparency.
2. Description of the Prior Art
In the past, aromatic polyester-polycarbonates have been prepared by reacting 2,2-bis-(4-hydroxyphenyl)-propane(bis-phenol A) or similar compound with a terephthaloyl chloride compound. It has been suggested that the starting materials should be reacted in a homogeneous system in an organic solvent containing pyridine and then allowing the resultant reaction mixture to undergo polycondensation with phosgene (Japanese Patent Laid-open Publication No. 128992/1977 and Goldberg, U.S. Pat. Nos. 3,030,331 and 3,169,121). By this technique an aromatic polyester-polycarbonate can be obtained which has excellent properties. However, because pyridine is used as an acid acceptor in the reaction, it cannot easily be separated from water because of its high solubility in water and because it possesses a boiling point which approximates the boiling point of water. During the polyester-polycarbonate reaction pyridine reacts with HCl liberated in the reaction and forms pyridine hydrochloride. However, when the hydrochloride is removed by treatment of the solution with aqueous alkali, significant quantities of pyridine are lost. Further, because pyridine has a very strong odor, it is difficult to comfortably work in areas where the reaction is conducted. Thus, this method has not been satisfactory from an industrial point of view. Therefore, a need continues to exist for a method by which aromatic polyester-polycarbonates can be prepared without using an acid acceptor in the reaction medium.